Basic Tile System Rendering Quick Mockup

SpriteSheet ss = a loaded spritesheet of 16x16, so the image is 512x512, x:0 y:0 is id:0, x:1 y:0 is id:1, x:1 y:1 is id:17, and so on

TileInfo[512] ti;
          ^-- # of unique tile types

//Init data
for (int x = 0; x < 16; x++) {
    for (int y = 0; y < 16; y++) {
        ti[(y*16)+x] = new TileInfo();
        ti[(y*16)+x].tileID = (y*16)+x;
    }
}

//Render your shit
void renderViewport() {
    //filler data just so i can render, this should of course be somewhere else
    int tileSize = 32;
    int worldSizeX = 9600 (300x32)
    int worldSizeY = 6400 (200x32)
    int viewportWidth = 800;
    int viewportHeight = 600;
    int viewportPosX = 133;
    int viewportPosY = 162;

    int viewportGUIX = 60;
    int viewportGUIY = 30;

    //now for the render - ignoring the need for smoothly clipping off the tiles along the viewport border
    int tileXStart = ((int)(viewportPosX / tileSize))
    int tileXEnd = ((int)(viewportPosX / tileSize)) + ((int)((viewportWidth / tileSize) + 0.5)) //0.5 to round up for that extra tile
    int tileYStart = ((int)(viewportPosY / tileSize))
    int tileYEnd = ((int)(viewportPosY / tileSize)) + ((int)((viewportHeight / tileSize) + 0.5)) //0.5 to round up for that extra tile

    //no wait, noooowwww for the render
    for (int x = tileXStart; x <= tileXEnd; x++) {
        for (int y = tileYStart; y < tileYEnd; y++) {

            Image tileImage = ss.getSprite(x, y);

            //bitblit?! source, x, y, width, height, dest, x, y, width, height
            OGLRenderMethodWhateverThatIs(tileImage, 0, 0, tileSize, tileSize, screen, viewportGUIX + (x * tileSize), viewportGUIY + (y * tileSize), tileSize, tileSize);

        }
    }
}